Renal Infarction

A 68-year-old man presents to the emergency room with a 2-day history of abdominal pain, nausea, and vomiting. He denies any urinary frequency or urgency and denies any recent changes in his diet. His temperature is 100.4°F (38°C) and pulse is 104/min. He has a past medical history significant for type II diabetes mellitus and coronary artery disease. He has had two stents in the past three years. On physical exam, there is bilateral flank tenderness upon palpation. A non-contrast computerized tomography (CT) scan without contrast is negative for urolithiasis. A CT scan with contrast reveals a wedge shaped perfusion defect in both kidneys.

Introduction

Clinical definition

complete occlusion of main renal artery or segmental branch

Epidemiology

incidence

very rare

0.7-1.4% found on autopsies

risk factors

cardiovascular disease

Etiology

cardioemboli

cardiomyopathy

endocarditis

artificial valves thrombi

renal artery injury and thrombosis

Marfan syndrome

trauma

polyarteritis nodosa

other vasculitidies

hypercoagulable states

hereditary thrombophilia

antiphospholipid syndrome

Pathogenesis

complete occlusion of main renal artery or segmental branch artery

Associated conditions

atrial fibrillation

Prognosis

11-12% mortality in first month after diagnosis

renal infarction occurs in patient populations with significant morbidity and mortality, such as atrial fibrillation

patients are at risk for future repeat renal infarctions

Presentation

Symptoms

acute onset abdominal or flank pain

nausea

vomiting

Physical exam

fever

acute elevation in blood pressure

may be mediated by renin release

tenderness to palpation of abdomen or flank

other signs of extrarenal embolization

focal neurologic deficits

Imaging

Spiral CT without contrast

indications

initial test for flank pain to evaluate for renal calculi

CT with contrast

indications

if there are no calculi seen on initial imaging

to evaluate for renal infarction

findings

wedge-shaped perfusion defect

80% sensitivity

Studies

Labs

↑ creatinine

but it can also be normal if embolus is unilateral

↑ lactate dehydrogenase (> 2-4x upper limit of normal)

little or no ↑ in serum aminotransferases

Urine studies

hematuria

proteinuria

Electrodiagnostics

electrocardiogram to evaluate for atrial fibrillation

Diagnostic criteria

in the correct clinical context, the combination of elevated lactate dehydrogenase and normal serum aminotransferase is strongly suggestive of renal infarction

note, this combination is also seen in transplant rejection, late myocardial infarction, and hemolysis, but these are clinically distinct from renal infarction

Differential

Renal atheroemboli

incomplete occlusion of distal vessels

will likely have eosinophilia, eosinophiluria, and hypocomplementemia

Nephrolithiasis

stones seen on imaging

lactate dehydrogenase is normal

Treatment

Medical

anticoagulation

indications

atrial fibrillation

hypercoagulable state

delayed diagnosiss

anticoagulation therapy is prophylactic to prevent future events

drugs

heparin followed by warfarin

Percutaneous endovascular therapy

thrombolysis and thrombectomy

indications

in patients who are diagnosed early

if diagnosed early, viable tissue may be saved with thrombolysis

Complications

Repeat thromboembolic events

Renal failure

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